Apple imac 17 inch User Manual

Logic Board Battery 
Important: Apple highly recommends removing the battery when handling the logic boa\
rd. Make 
sure to use proper ESD protection when handling modules. 
The battery on the logic board controls the stored system settings, such\
 as date and time. It is 
only necessary to test the battery when you can’t power on the comput\
er, or the date and time are 
reset every time the AC power is removed. 
The battery is also used to power the PMU chip (because the PMU chip ke\
eps time and must...

Thermal Paste Application 
The following instructions explain how to apply thermal paste to the thermal pipe in the iMac (Flat Panel) 
computer. Failure to follow these instructions could cause the computer to overhe\
at and damage internal 
components. 
Tools 
This procedure requires the following tools: 
• Plastic stylus or nylon probe tool (922-5065) to remove the old therma\
l paste 
• Thermal paste (922-4757), each tube contains 4-5 applications 
Procedure 
1.	Thoroughly clean the thermal film from...

2 Squeeze a drop of thermal paste onto the middle of the thermal pipe surf\
ace as shown below. 
Note: In testing, the drop of thermal paste shown below completely covered the\
 entire 
thermal pipe surface. Place at  least this much paste on the thermal pipe. 
3.	Close the bottom housing. Securely fasten the four mounting torx screws very firmly (at least 17 in.– 
lbs. is necessary).  Important: If you don’t have access to a calibrated torque driver make certain that 
the screws are tightened firmly. You...

Thermal Pad Replacement Instructions 
The following instructions explain how to replace the thermal pads in the iMac (Flat Panel) computer. These 
pads must be changed each time the main logic board is removed from the \
bottom housing.
 No tools 
are required for this procedure 
Procedure 
1.	Remove the old thermal pads (circled below) from the bottom housing.  Note:  If you don’t see all three 
thermal pads on the bottom housing, check the bottom side of the logic board. 
2.	Using the thermal pad kit,...

Symptom Charts

How to Use the Symptom Charts 
The Symptom Charts included in this chapter will help you diagnose specific symptoms related to the 
product. Because cures are listed on the charts in the order of most likely solution, try the cures in the 
order presented. Verify whether or not the product continues to exhibit the symptom. If the symptom 
persists, try the next cure. 
Note:  If you have replaced a module, reinstall the original module before you proceed to the next cure. 
Apple Hardware...

No Power 
The computer will not power on. 
1.	Verify the power outlet is good. Plug a different device into the socket to ensure there is power, or plug 
computer into another outlet. 
2.	Check the power cord. Use a known good power cord. 
3.	Check connection of the power cord on both ends. Verify that the plug is securely plugged into both the 
A/C outlet and back of the computer. 
4.	Remove keyboard, mouse, and other peripherals such as speakers. 
5.	Disconnect the power cord, place the computer in...

11. Check power supply output. Disconnect the diagnostic power cable from the power supply connector, 
and measure power at the power supply connector by touching the black probe to the ground pin, and 
using the red probe to measure power at the pins indicated in thegraphic below. Did you measure +12v 
at each point? If yes, continue with the next step. If no, replace the power supply. 
12. Check the main logic board voltages. Measure for +12v DC at capacitors C187 and C197 (identified in 
graphic...

No Video 
The screen is dark, fan and hard drive are spinning. 
1.	Reset parameter RAM. Press Command-Option-P-R during startup before “Welcome to Macintosh” 
appears. 
2.	The system software could be damaged. Start up from the system CD that came with the computer. 
3.	Remove the user access panel. With the unit powered on, check if a red LED (shown below) is visible in 
the access door. If the red LED is on, power is on. If you don’t see the red LED glowing red, follow the 
steps under the “No Power”...

8. Replace the inverter board. 
9. Replace the LCD display. 
10. Replace the neck assembly 
11. Replace the logic board. 
12. Replace the power supply board. 
18 -iMac (Flat Panel) Troubleshooting 
No Video Symptom Charts  

Display 
When displaying a single color over the screen area, the LCD panel shows one or more pixels 
that are not properly lit 
Active-matrix LCD technology uses rows and columns of addressable locations (pixels) that render text and 
images on screen. Each pixel location has three separate subpixels (red, green, and blue) that allow the 
image to be rendered in full color. Each subpixel has a corresponding transistor responsible for turning the 
subpixel on or off. 
There are typically millions of...